dominant mechanism of heat transfer is conduction, although convection occurs in the upper mantle and, while accounting for less heat transfer, the flow of molten rock is the cause of tectonism in the lithosphere

Plate Tectonics

tekton (Gr): carpenter or builder

outer 100 km of the earth (lithosphere) is composed of rigid plates

convection in the partially liquid asthenosphere causes shearing of the molten rock and shearing stress applied to the lithosphere

determines continental relief and volume of the ocean basins, and distribution of rock masses with varying lithology and structure

three types of contact at plate margins

constructive: plates moving apart; molten rock injected adding new rock to the trailing edge of the plates and creating ridges, mostly on the floors of ocean basins

occurs along destructive plate margins by crustal shortening and compression and thus in long narrow belts

associated with volcanoes and earthquakes (e.g. the circum-Pacific orogenic belt)

Epeirogenesis (Gr. epeiros: continent)

uniform, widespread crustal deformation with little or no faulting or folding

isostasy: the equilibrium maintained by crustal blocks because with increasing depth crustal rocks are denser and denser; therefore they subside with
increasing mass (e.g. sedimentation or glaciation) and rebound with decreasing mass (e.g. deglaciation or erosion)

thus there is an absolute limit to the earth's relief since the crust is always moving towards an equilibrium elevation

various kinds of lava: scoria is vesicular (bubbly) because alot of gas escapes as it cools; aa forms an angular blocky surface, pahoehoe is smooth and twisted (ropy) as it is hot fluid lava, pillow lava is pahoehoe lava that flow into or erupts into water, lava tubes flow out of a cooling hardened exterior